Oklahoma Democratic gubernatorial candidate Joe Dorman notified the state Election Board on Thursday that he was withdrawing his challenge to the candidacy of Kimberly Willis, who is running for governor as an independent.

The challenge contended that she was not registered as an independent for the six-month period required for her to run as an independent.

Willis said she has been an independent for longer than required and was in contact with election officials to clear up the matter.

Dorman is the only Democratic candidate against Republican incumbent Mary Fallin.

Chad Moody and Dax Ewbank also are running as Republicans. Richard Prawdzienski is running as an independent.